The present invention relates in general to the field of modular electronic systems, and more particularly to a method and system for cooling a card shelf.
Modular electronic systems are generally configured as a card shelf to optimize space efficiency within a central office or other similar facility. Card shelves include individual plug-in electronic module cards having different functions that communicate across a backplane. The electronic cards may have different thicknesses depending upon the amount of electronic circuitry contained in each electronic card. The electronic cards may also have flanges on the top and bottom which fit into grooves in the card shelf for sliding the electronic cards into the card shelf and plugging the electronic cards into connectors located in the backplane of the card shelf.
During operation, the electronic cards generate thermal energy, causing the electronic cards to retain heat. Because high temperature levels may impact the operational effectiveness of the electronic cards, the electronic cards must be cooled to prevent a malfunction of the electronic card. Active or passive cooling methods may be employed. For example, the card shelf may also include an open or perforated top and bottom portion to allow thermal energy generated by the electronic cards during operation to escape the card shelf. Additionally, the card shelf may include a fan assembly for directing airflow through the card shelf to dissipate thermal energy generated by the electronic cards during operation. The fan assemblies may include air filters to purify air and remove harmful dust and other contaminants.
Known card shelves also present certain other drawbacks. For example, to maximize space within a card shelf, electronic cards are placed in close proximity to one another. As a result, dissipation of thermal energy generated by the electronic cards during operation may be difficult or inadequate to maintain proper operation of the electronic cards. Thermal energy generated by the electronic cards may cause a fire to ignite within the card shelf thereby damaging one or more of the electronic cards.
Including fan assemblies in known card shelves also presents certain drawbacks. For example, a partially filled card shelf may cause airflow generated by the fan assembly to be directed around the electronic cards to areas of less resistance. Although dummy cards may be inserted into the card shelf to compensate for misdirected airflow, a variety of sizes of dummy cards must be maintained to replace removed electronic cards or fill open areas in the card shelf. Furthermore, airflow generated by the fan assembly may cause acceleration and/or propagation of a fire ignited within the card shelf.
The present invention provides an improved method and system for cooling a card shelf that substantially eliminates or reduces the disadvantages and problems associated with previous systems and methods. In particular, inlets are provided in the electronic card cover plates for receiving an airflow to passively cool the electronic cards during operation.
In accordance with one embodiment of the present invention, a method for dissipating thermal energy from a card shelf includes providing an electronic card disposed in the card shelf and receiving an airflow through an inlet disposed in a cover plate of the electronic card. The method also includes passively passing the airflow adjacent a circuit board of the electronic card to dissipate the thermal energy generated by the electronic card.
According to another embodiment of the present invention, a card shelf includes a backplane and a plurality of side support members disposed proximate the backplane. The card shelf also includes a top support member disposed proximate the backplane and a bottom support member disposed opposite the top support member. The plurality of side support members, the top support member, and the bottom support member form a shelf area configured to receive electronic cards. At least one of the electronic cards comprises a cover plate having an inlet operable to receive an airflow to dissipate thermal energy generated by the electronic card.
In accordance with yet another embodiment of the present invention, an electronic card for a card shelf includes a circuit board having a plurality of electronic devices coupled thereto, and a cover plate coupled to the circuit board. The electronic card also includes an inlet disposed in the cover plate. The inlet is operable to receive an airflow to dissipate thermal energy generated by the electronic devices.
Technical advantages of the present invention include providing an improved method and system for cooling a card shelf. In particular, airflow inlets are provided at a lower level of the cards. This allows airflow to enter the card shelf in close proximity to the location of the electronic devices of the electronic card that are to be cooled. Additionally, airflow inlets provided in the electronic cards substantially alleviates the requirement for other cooling devices or structures near the lower portion of the card shelf, thereby creating additional vertical length of the electronic card for the inclusion of additional components and functionality of the electronic card.
Another technical advantage of the present invention includes providing an improved cooling system for a card shelf. In particular, a filter and air inlets are provided at the front of the card shelf. This allows for easier user observation of the air filter which, in turn, leads to more frequent cleaning as the air filter is more readily observable and accessible to the user. Additionally, by locating the filter in front of the card shelf, and by maintaining proper maintenance of the filter, the card shelf life itself is extended.
Still another technical advantage includes providing an improved cooling system for electronic cards. In particular, a filter/diffuser assembly includes a diffuser component which extends into the interior of the card shelf. The diffuser component serves to diffuse the airflow entering the card shelf through the airflow inlets such that the airflow is distributed substantially evenly about the electronic card or directed towards the warmest or most thermally active components of the electronic card. Thus, the efficiency of the cooling method increases, thereby allowing for a greater number of components on each card and larger cards.
Other technical advantages of the present invention will be readily apparent to one skilled in the art from the following figures, descriptions, and claims.